The present invention relates to a metallic golf club head having a hollow space.
Conventionally, since the head of a driver has been made of stainless steel, the head volume has been as small as 150 to 200 cc. Since the hitting sound of this head is too loud, urethane foam or the like has been contained in the hollow part of the head to keep the hitting sound soft. However, in the 1990s, a golf club head made of a titanium alloy by the casting method made an appearance, and therefore the driver head became large in size. At that time, the head volume was about 250 cc. However, the material and manufacturing method of titanium alloy and the like have been improved, and at the present, a large head having a volume exceeding 400 cc appears. If the head size increases, the sweet area of head expands, so that a user-friendly golf club such that the decrease in carry is less even at an off-centered shot can be manufactured. However, if the head having a hollow part is made large, the thicknesses of members constituting a crown part and a sole part decrease, and also the area of the hollow part increases, which presents a problem in that the hitting sound becomes too soft.
Japanese Unexamined Patent Application Publication No. 2002-186691 describes a golf club head in which to make the hitting sound of a golf club head loud, in a hollow space of the golf club head, plate-shaped ribs are provided ranging from a sole part to a back face part.
On the other hand, various proposals for the configuration of a crown part of golf club head have been made.
For example, Japanese Unexamined Patent Application Publication No. 7-284546 describes a golf club head in which the wall thickness of a central part occupying a half or more of the total area of a crown part is made less than 1.2 mm, and the weight removed by this decreased thickness is distributed to other parts, by which the sweet area is expanded and the moment of inertia is increased. Also, Japanese Unexamined Patent Application Publication No. 2007-54198 describes a golf club head in which a thick-wall part is provided on the whole circumference of a crown part, on the inside thereof, a thin-wall part having a thickness smaller than that of the thick-wall part is provided, and the similar thick-wall part and thin-wall part are provided in both side parts on the toe side and the heel side, by which the delivery angle is increased, and thereby the carry is increased.